Nature or nurture. One of the most intense debates in understanding the development of the human mind is whether cognitive ability is based in genetics or developed through learning experiences. While biology clearly plays a part, recent neuroscience research shows that the interactions experienced during infancy and childhood can actually change the physical structure and wiring of the brain. Does this mean many children with developmental and learning disorders--such as autism, PDD, language and speech problems, ADD, Down syndrome and others--can make greater progress than previously thought? The pioneering work of Stanley Greenspan and Serena Wieder strongly supports this prospect.